Global broadband wireless communications have been growing exponentially in recent years. Network coverage, however, remains incomplete in many regions of the world and even in some currently served regions; thus demand may soon exceed the supply of existing communication infrastructure. Current network technologies are generally too expensive, ineffective, and slow to respond to growing demand.
In addition, further proliferation of existing ground-based wireless technologies increases radio-frequency (RF) pollution and human exposure to large amounts of RF energy. Many people are concerned that RF exposure might have the potential to cause certain types of cancer and other health problems. Antennas for wireless communications are typically located on towers, water tanks, and other elevated structures, including building sides and rooftops. RF emissions within 100-150 feet of a cell tower can exceed FCC limits. The standard approach to increasing wireless capacity by increasing the number of ground-based antennas per unit area will inevitably lead to an increase in the RF exposure to potentially hazardous levels.
Alternatively, there have been proposals to establish aerial networks that employ airborne platforms as additional communication hubs. Such hubs would be stationed at altitudes well above commercial airspace, where the line of sight coverage extends over large terrestrial areas and the average wind-speeds are low. These solutions were proposed as alternatives to satellite communication systems, rather than terrestrial mobile phone communication systems. Closer consideration of earlier proposals and initiatives in this area reveal many shortcomings in the defined missions, platforms, and supporting technologies as hurdles for their successful implementation. As a result, none of these proposals have been realized in practice so far.
Current broadband services are delivered via wired (e.g., optical fiber) and terrestrial wireless (e.g., cellular) networks with satellite and radio links providing auxiliary coverage beyond the reach of such networks. The inventors have observed that each of these solutions have significant constraints limiting their application and leaving many gaps in covered areas.
For example, optical fibers are well suited for fixed high-capacity links between high-usage points including continents, cities, metro-area networks, and so on. However, they require physical installation, which is expensive and may not always be practical. In addition, optical fibers are not appropriate for mobile end users.
Terrestrial cellular wireless networks are well suited for local area deployments. They are relatively inexpensive, as compared to optical fiber networks, and are the technology of choice in new and emerging markets where the physical infrastructure is limited. Terrestrial cellular wireless networks are appropriate for fixed and mobile users and may be interfaced to wired networks. However, as discrete components, they are range limited and have finite bandwidth. To meet an increasing customer demand, new towers are added to increase the coverage density, while reducing their range to enable increased frequency reuse.
Satellite links can provide additional coverage to remote and underserved regions, but they operate at RF frequencies different from those of terrestrial wireless networks, have low signal strength and require different hardware. In addition, communication satellites are extremely expensive, experience signal delays, and have bandwidth limitations.
Thus, the inventors believe that there is a need for an improved and more effective communication system architecture.